Abstract 1596: Detection of PD-L1 in cell surface vimentin positive circulating tumor cells is associated with poor survival in cancer patients

Abstract

Abstract Circulating tumor cells (CTCs) are the cells that detach from the primary tumor of patients and enter in to the blood stream and these can be represented as the seeds of metastasis. Increasing evidence has shown the detection of circulating tumor cells (CTCs) from blood of cancer patients parallels with tumor burden and is associated with poor prognosis. Although CTC counts change indicates a good modality to detect therapeutic response to drug treatments, there is an increasing need of a reliable marker that can be used to predict survival in cancer patients. One of the most prevalent markers detected in cancer patients is the cell surface glycoprotein called PD-L1 (also called B7-H1 and CD274). Aberrant expression of PD-L1 has been reported in several cancer types. Here in this study we tested the hypothesis that detection of PD-L1 in CTCs is associated with poor prognosis. To validate the hypothesis, we isolated cell-surface vimentin (CSV) positive CTCs from colorectal cancer patients using 84-1 method and analyzed for PD-L1 expression. Our results indicated that PD-L1 detection in CTCs was associated with poor overall survival (HR, 2.43; 95% CI, 1.11 to 5.35; p, 0.0264) in colorectal cancer patients undergoing treatment. These findings thus suggest that PD-L1 detection in CSV CTC could serve as a new prognostic tool. We further extend our observations in other types of cancers including breast, prostate and sarcoma. Citation Format: Arun Satelli, Zachary Brownlee, Hyangsoon Noh, Qing H. Meng, Scott Kopetz, Michael Overman, Shulin Li. Detection of PD-L1 in cell surface vimentin positive circulating tumor cells is associated with poor survival in cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1596. doi:10.1158/1538-7445.AM2015-1596